N° 5–2000: Largest ozone measurement campaign ever over the Arctic

24 January 2000

The European Space Agency is contributing to the world's biggest field campaign to measure ozone amounts and changes over the Arctic. The aim of this international campaign is to obtain a better understanding of the low ozone values observed over the Arctic region during recent winter/spring seasons and their possible link to long-term ozone depletion over Europe. The campaign, based above the Arctic Circle in the Kiruna area, Sweden, started last November and continues until the end of March.

Throughout the campaign, the Arctic/Northern European upper atmosphere is being monitored by 30 ground-based instruments, European and American planes, and up to 600 ozone sonde (balloon) launches. These observations are complemented by measurements from Earth observation satellite instruments including the Global Ozone Monitoring Experiment (GOME) on board ESA's ERS-2 satellite.

Under cooperation arrangements among the Institutes of Environmental Physics (IUP) at the Universities of Bremen and Heidelberg respectively, the Remote Sensing Data Centre at the German Aerospace Centre (DLR/DFD), the Dutch Space Research Organisation (SRON), the Norwegian Institute for Air Research (NILU), the Swedish Space Corporation (SSC), and the European Space Agency (ESA), scientists are being provided with GOME data such as total ozone columns, ozone profiles, nitrogen dioxide, bromine monoxide, and chlorine dioxide maps in near real time for the coordination of field experiments in regions of interest.

The Earth's ozone layer screens and protects us and other life forms from harmful ultraviolet radiation generated by the Sun. Over 15 years ago, scientists detected an "ozone hole" over the South Pole which has reappeared each year during the southern hemisphere winter and spring. Scientists from all over the world have recognised that ozone depletion is caused mainly by man-made chlorine and bromine compounds.

In recent years, ozone depletion has started affecting the Arctic region as well, with peaks of depletion reaching 50%. If the Arctic upper atmosphere remains very cold this winter we shall see large-scale ozone depletion in the Arctic after mid-February, as has been observed in a number of winter/spring seasons during the 1990s.

Climate modelling suggests that global warming in the troposphere is cooling the upper atmosphere. Polar winters may therefore be expected to become colder in coming decades. The consequence would be that despite the reduction in emissions of chlorofluorocarbons (as fostered worldwide and enforced through international treaties), any reversal of global ozone depletion may be delayed by several decades.

The next generation of European Earth observation satellites will carry on the quest for a better understanding of the possible connection between chemical ozone depletion and climate change. ESA's environmental satellite Envisat, due to be launched in 2001, will carry three instruments even more powerful than GOME. In addition, GOME follow-on instruments will be employed on the three METOP satellites being prepared by ESA for the European Organisation for the Exploitation of Meteorological Satellites, Eumetsat. Both systems will ensure continuity of global monitoring of environmental change over the next two decades.